This invention relates to apparatus for and to a method of cutting carpet. The invention is particularly intended for use in cutting carpet into tiles, for example in cutting tiles from rolls of bonded carpet the manufacture of which is described in British Pat. No. 1,421,062 and 1,422,524.
Carpet is generally manufactured in long lengths and carpet tiles are formed from the lengths by a cutting up operation. Hitherto the positions of cuts made in such lengths of carpet have not been accurately predetermined. Precise cutting has hitherto been avoided by manufacturing plain carpet tiles or tiles with a random pattern, in which cases the precise position of the cuts is not important, and by printing pre-cut tiles.
The invention provides a means whereby carpets with repeated patterns can be cut at suitable parts of the pattern to form tiles which can be abutted in any sequence to reform the pattern.
British Pat. No. 1,338,030 of Sidlaw discloses the forming of carpet tiles by cutting the backing only of a piece of carpet (hereinafter referred to as a pelt). The Sidlaw patent makes no reference to a pattern on the carpet and fails to disclose means which would enable a predetermined position between the pattern on the carpet and the cutting tool to be established. Furthermore, the patent teaches that a strip of waste should always be left between adjacent tiles cut from a single pelt so that only one side of any line of cut forms an edge of a tile. Clearly, if the Sidlaw procedure was applied to patterned carpet, it would not be possible to reform a pattern present on the pelt by abutting carpet tiles after cutting and removal of the waste. The Sidlaw procedure and apparatus is not useful for patterned carpet.
The application for the Sidlaw patent was filed on June 12th 1971 and referred to methods in use prior to that date for cutting carpet tiles from lengths of carpet. This shows that the manufacture of carpet tiles from lengths of carpet which do not have a regular pattern has been carried out for well in excess of ten years. However, the problem of cutting accurately patterned carpet to make carpet tiles has not been solved prior to the present application and patterned carpet tiles having a pattern established during construction of the carpet have not been manufactured.
In order to cut satisfactorily carpet tiles from a pelt, each cut must be made between a pre-selected pair of rows of pile tufts and, in each successive tile, the corresponding cut must be made between corresponding rows of tufts. Means for indicating to an operator the position of the pattern on a piece of carpet with the required degree of accuracy and which is suitable for use in commercial production of carpet tiles has not been known in the art, prior to the present invention. It will be understood that the dimensions of pieces of carpet cannot be controlled within close tolerances to ensure that successive pelts will have the same dimensions and will have the pattern correspondingly positioned, within the tolerances necessary to cut between a pre-selected row of tufts, and that commercial production of patterned carpet tiles can be viable only if each successive pelt can be positioned quickly for cutting.
British Pat. No. 1,181,731 of Stafford Tool and Die Company discloses apparatus for cutting pieces of textile material of predetermined size and shape from larger pieces. The apparatus includes a cutting blade and spikes on which the larger pieces of material can be impaled. No suggestion is made that a predetermined relation between the cutting blade and a pattern on the pieces of material could be established. The spikes pierce the textile material from below and piercing of a piece of carpet at predetermined postions with respect to a pattern on the upper face would not be practicable. Furthermore, the spikes are spaced substantially from the cutting tool so that piercing of a piece of textile material by a spike at a predetermined position in a pattern on the material would not ensure cutting of the material exactly at a pre-selected position by the cutting blade.
Apparatus for establishing registration of pattern on successive pieces of fabric incorporated in a stack is disclosed in British Patent Application No. 2,045,724 of Rhomberg. This apparatus includes two spot-lights which project images of respective graticules onto the surface of the fabric so that selected elements of the pattern can be adjusted to the positions of these images. An image of a graticule projected by a light source onto patterned pile fabric cannot be seen sufficiently clearly to facilitate rapid, accurate positioning of the pile fabric relative to the graticule. The procedure described in Application No. 2,045,724 is proposed for cutting out pieces of fabric which are to be used in the construction of garments. The cutting of carpet at predetermined positions in a pattern of the carpet has not previously been contemplated in the art, owing to the lack of knowledge as to how the carpet could be positioned sufficiently accurately and quickly relative to a cutting blade.
In U.S. Pat. No. 3,400,925 issued to Tobias, there is disclosed apparatus having a transparent plate with an edge along which a tool for cutting sheet material underlying the plate can be moved. The sheet which is to be cut is placed on a fixed surface of the apparatus and the transparent plate is moved until the edge thereof is at a selected position on the sheet. The sheet is then cut along the edge of the plate. This arrangement is used for cutting a line of type-written characters from photo-composed text, in order that a line containing an error can be replaced by corrected text. The cutting tool is applied to that face of the sheet which is engaged by the transparent plate. This apparatus would not be useful in the production of patterned carpet tiles. The movement of the transparent plate to bring an edge thereof into coincidence with successive lines where a carpet pelt is to be cut would require an excessive period of time for the cutting of each tile. Furthermore, cutting would damage the pile tufts.
Apparatus with a pointer to assist positioning of a workpiece is disclosed in U.S. Pat. No. 1,166,261 issued to Rogers. This patent discloses a press equipped with a punch and with a movable pointer having a tip which occupies the position at which the centre of the punch will engage the workpiece, until the punch descends. The pointer is then automatically moved out of the path of the punch. Whilst this apparatus may be useful to enable a user to position a centre mark on a workpiece in the path of a centre of a punch, it would not enable a carpet pelt bearing a pattern to be positioned with the pattern in a predetermined relation to a cutting blade for cutting a tile from the pelt. Even if the pointer disclosed in the Rogers' patent was duplicated, the pointers would not be convenient for positioning a carpet pelt. To position accurately the pattern on a piece of carpet in relation to cutting blades, it is necessary for an operator to view the piece of carpet from above and to have a similar view of different parts of the pattern. In the Rogers' apparatus, an operator is prevented by the press from occupying a position from which a satisfactory view of a piece of carpet could be obtained. A person skilled in the art of carpet tile manufacture would not be led by the Rogers' patent to adopt the Rogers pointer in a press for cutting carpet tiles, since the pointer would clearly be inadequate to solve the problem of accurate positioning of patterned carpet.